Add co2 documentation

app.py

@@ -432,6 +432,11 @@ async def query_endpoint(request: QueryRequest):
         - sources (list): Source documents used for context
         - explanation (str): Explanation of the retrieval and answer logic
         - total_token (int): Total token count from the LLM call
+        - prompt_tokens (int): Prompt token count
+        - completion_tokens (int): Completion token count
+        - cached_tokens (int): Cached prompt tokens (when reported by provider)
+        - co2_grams (float | None): Estimated CO2 emission in grams (via ecologits)
+        - energy_kwh (float | None): Estimated energy use in kWh (via ecologits)
         - run_time_in_ms (float): Pipeline execution time in milliseconds
     """
     logger.info(f"Query received: {request.query}")